Dual lifters have two side-by-side hydraulic lash adjusters mounted in a common elongated housing and are used in internal combustion engines with four or more valves to simultaneously act on two side-by-side valves of the same cylinder. One end of the housing has a cam follower and the other end is open so that the hydraulic lash adjusters can contact push-rods or finger followers of the side-by-side valves. Such dual lifters act simultaneously on both valves so as to affect opening and closing of the valves.
There is a need to de-activate one of the side-by-side valve when using a dual lifter in order to increase fuel efficiency of the engine.